Space telegraphy.



No. 767,981. PATENTED AUG. 16, 1904. LS. STONE.

- SPACE TELEGRAPHY.

APPLICATION FILED NOV. 25, 1903.

,NO MODEL.

WITNESSES- UNITED STATES,

Patented August 16, 1904.

PATENT OFFICE.

JOHN STONE STONE, OF CAMBRIDGE, MASSACHUSETTS, ASSIGNOR TO WILLIAM W. SWAN, TRUSTEE, OF BROOKLINE, MASSACHUSETTS.

SPACE TELEGRAPHY.

SPECIFICATIONforming part of Letterslatent No. 767,981, dated August, 16, 1904;.

Application filed November 25, 1908. Serial No. 182,628. (No model.) v I To all whom it may concern.-

Be it known that I, JOHN STONE STONE, a citizen of the United States, and a resident of Cambridge, in the county of Middlesex and State of Massachusetts, have invented a certain new and useful Improvement in Space Telegraphy, of which the following is a spec1-' fication.

This invention relatesto space or wireless telegraphy by electromagnetic waves in the troreceptive devices to selective electric signaling and have therein pointed out that in order to be sensitive and rapidly responsive to changes in thermal conditlon the fine wires or strips of such bolometers should be of small thermal time constant compared with the thermal time constant of the bolometers heretofore used and that in order to be of small thermal time constant the fine wires or strips should have small mass, 6., they should be that as the oscillatory currents developed inv the receiving-conductors of space-telegraph systems are of small amplitude it is necessary to employ some means whereby the currents developed in the receiving system by electromagnetic waves may be amplified in order that an appreciable amount of energy may be dis sipat ed in thebolometer wires or strips without makingthe latter of excessively high resistance. For amplifying the currents developed in the receiving system by electromagnetic waves of a definite predetermined frequency I employ a resonant circuit or a group of resonant circuits attuned to such frequency. The resonant'circuits strongly oppose the development therein of currents of frequencies different from that to which they are tuned,

so that by means of such resonant circuits the bolometer fine wires or strips are protected from extraneous electrical forces which might otherwise destroy them.

The reason the bolometer strip or wire is preferably made of a material having a high specific resistance is to obtain the smallest possible mass with wires or strips of a given resistance. Although the specific resistance of the material of which the wire or strip is pref: erably constructed should be high, the actual resistance of the wire or strip itself should be low, so as not to; mask the resonant rise of current in the resonant circuit in, which the wire or strip is included, as I have pointed out in my prior patents in which other forms of receivers or wave-detectors are employed 4 and in which I have shown that the selectivity of a resonant circuit varies inversely as the resistan ce of such circuit and is, in fact,equal By employing a resonant circuit it is pos sible to use bolometer wires or strips of much larger mass than it would otherwise be possible to use in order to efiect the dissipation of a given amount of energy in said wires or strips. It is not, possible to lay down any specific rule concerning the mass or geometric constants of the bolometer wire or strip, as such mass must be determined by the amount of energy radiated in the .form of electromagnetic waves and by the distance over which transmission is to take place and as it must also be determined in a way by the locality in which the receiving station is placed z'. e. if the receiving-station is placed in a locality .free from electromagnetic disturbancesthe wire or strip may beof smaller mass than if it be placed in a locality subject to frequent and violent electrical disturbances. By having regard to the electrical conditions surrounding the proposed receiving-station safety of the latter may be better insured, although it follows in a general way that more energy must be employed to transmit signals over a given distance when the bolometer wire or strip is required by the electrical characteristics of the locus of the receivingstation to be of larger mass than if the wire or strip is made of the minimum possible mass, and therefore of the maximum sensitiveness.

Dr. VVollaston has described a method for producing Wire of excessively small diameter, which method consists in incasing a fine platinum wire in silver, reducing the composite wire so formed, and then dissolving away the silver casing with warm nitrous acid. In this way wire of diameter as small as one fifty-thousandth of an inch was produced, as fully set forth on page 615 of the Encyclopedia Britannica, 9th edition, Vol. XXIV, published by Little, Brown 8: (10., Boston, 1888, in an article entitled Wire, to which all those wishing to practice my invention are referred for further details concerning the manufacture of wire suitable for use in the bolometer described herein, although such wire has long been in commercial use and may be obtained and, in fact, is usually obtained before the silver casing has been removed. The manufacture of such wire is also described in a publication entitled A Zl'catisc apon lVirc, by J. Bucknall Smith, published by John Wiley &Sons, New York, 1891, page 10, and it was first described by Dr. VVollaston in the Philosophical Transactions 0 f t/zc Royal S0- cict e of London, 1813, Vol. 103, part I, page 114. Such wire so produced may be employed in the system herein described, and Ialso recommend the employment of a bolometer-strip produced as follows: A sheet of gold-leaf, which may be one micron in thickness or greater, is cast in ablock of paraffin and sliced by a microtome into strips of any desired width, which may be as small as one micron in width, after the manner in which stained sections well known in microscopic biology are produced. In lieu of the gold-leaf of commerce I may deposit gold electrolytically on a conducting backing, dissolve away the backing, and treat the resulting gold-leaf as above explained. The strips of gold-leaf produced by either process or a short length of platinum wire produced by the VVollaston process may bemounted for use in a bolometer in the following manner, so that a very small length of the strip or wire is operative as a source of resistance in the resonant circuit: On a perfectly plane glass plate deposit a silver film in the manner now well known, and upon this film of silver electrolytically deposit a much thicker film of some softer metal, as gold, copper, &c. The thickness of this second film is several times the thickness of the bolometer wire or strip. The surface so produced may be polished or burnished. Across the surface so surface.

produced a line should be scratched by an extremely fine-edged engraving instrument, dividing the surface into two parts electrically insulated from one another by the line so scratched, as shown by connecting the twosurfaces to a battery and a highly-sensitive galvanometer. Across this scratch the bolometer wire or strip should be laid so as to form an electrical connection between the two separated metalfilms, when a slightly convex surface of glass is pressed down on said strip or The bolometer as now mounted is ready for use, the connections bein made with the two metallic surfaces as terminals. The device is preferably maintained in an atmosphere of hydrogen or nitrogen or other gas which will not support combustion of the material'of the bolometer strip or wire, said gas being preferablymaintained at as low a temperature as practicable. liy so maintaining the gas at such low temperature I can control a greater amount of current by a given change of resistance in the bolometer strip or wire, and so have a greater amount of energy available for the operation of the signal-indicating device. In order to maintain the balance of the Vheatstones bridge or induction-lialance in which the bolometer is included, it is preferred to maintain this low temperature constant.

In the drawings which accompany and form a part of this specification, Figures '1, 2, and 3 illustrate in diagram arrangements of circuits and apparatus at a space-telegraph receiving-station. Fig. A is a plan view of the bolometer with the upper slightly convex glass plate removed. Fig. 5 is a section taken on lines 5 5 of Fig. 4:. Fig. 6 is a section taken on lines 6 6 of Fig. 21:.

V is an elevated conductor. hi H are transformers, preferably step-down transformers. C C are condensers. L L are imluctances. L L are choking-coils. L is an impedance. I I constitute the primary, and I the secondary, windings of the inducti(in-balance. 'l is a telephone or other signal-indicating device. B is a bolometer consisting of four wires or strips 1, 2, 3, and 1 of equal resistance. B is a bolometer consisting of a single wire or strip 1. A is asource of rapidly-varying current, which may consist of an electrically-actuated tuning-fork carrying )ermanent magnets, the movement of which tuning-fork creates a rapidly-varying electromotive force in an associated circuit.

Referring to Figs. 4:, 5, and 6, 1/ represents a perfectly plane glass plate upon which a layer of silver s is electrolytically deposited, and 0 represents a somewhat thicker layer of softer metal, such as gold or copper, deposited on said layer of silver. 7/ represents the scratch produced by a very tine-edged engraving instrument across the aforesaid films. 1 represents the bolometer strip or wireconnecting the two sections of the deposited mebalance in which the bolorneter is included? by' including in one arm thereof a resistance: R equal to the resistance of the bolometer B- or B included'in the other arm of said balance,.as indicated in dotted lines in Figs. 1, 2, g and 3, although. asindicated, a bolometer identical. with'that in the resonant circuit may be used to balance the induction-balance. It is preferred to employ an iinpedance L in the circuit of'the source A. r 1

The operation of'the system is as follows? Electrical oscillations developed in the elevated conductor V by electromagnetic signal-" waves the energy of which'is to be received are conveyed to the closed resonant circuit C L LB, C M LB, or-G M L Min Figs. 1, 2,'an d'3, respectively,- said resonant circuits operating to -greatl'y increase the amplitude} of the oscillations, as I havepointed out in my prior patents. In FigsJI and 2"the electrical oscillations so amplified increase the temperature, and therefore the resistance of the bol'orneter wlres o'r"'strips, and thisincrease of resistance unbalances thelnductionbalance and e'ffectsthe indication -'of-' asignal in the telephone or other signal iildicating device T,

In Fig. 3 the electrical oscillations or cur-i rentsdeveloped in the resonant circuit GM L M are translated to the resonant circuit 'C M L B, attuned to the same frequency oscillations developed by electromagnetic,

Waves in the elevated conductor vV are inductive'ly reproduced at jincreased c'urrent in the resonant circuit 0 ML B'by means of the step-downtra'nsformer M, and in the systemv shownin Fig. -3 the electrical oscillations inductively reproduced at increased current in the resonant circuit C M L M by meansof the step-downtransformer M are inductively reproducedat still further increased current in the second resonant circuit C M L B by means of'the second step-down trans-= former M. i i

It will be observed-that the the loolorneter strips or wires in Figs. 1 and 2 is such as to prevent the electric'oscillations developed in the resonant circuits from takingany path other thanthrough' the bolom-- 9 represents the slightlyconarrangement of eter strips,'because said strips constitute abalanced 'Wheatstone bridge, at the equipotential points of which the connections to the induction-balance are made.

In Fig. 3, which shows another embodiment of my invention in which the wireor strip is employed, some means must be used to prevent the shunting of the electrical oscillations developed in the circuit M L B C around the bolometer wire or strip B by way of the induction-balance; For this purpose. I employ specially-designed inductance -.coils L L, placed in each of the arms of the induction-balance. These inductance or choking coils are wound so as to have the greatest possible inductance'with the leastpossible electrostatic capacity. For this purpose the windings of said coils are separated'and cores of finely-dividedsoft iron of the best magnetic quality, preferably cast in a dielectric matrix, are used; 'I-Ieretofore in designing choking-coils a number of turns of fine insulated wire have been wound closely together upon an iron core, so that although such coil has acertain amount of inductance it usually behaves'more like a condenser than like a coil having fixed resistance and inductance and no capacity. For this reason excessive displacement-Currents are developed between the windings of such coils, and a large portion of the'energy of the high-frequency electrical oscillations is'shunted around the receiver by way-ofsaid choking-coils instead of being confined to the circuit containing the receiver.

With an inductance or choking coil designed as hereinbefore set forth the energy of the electrical oscillations in the resonant circuit containing the bolometer B" is practically entirely confined to said resonant circuit and that portion of this energywhich is shunted around said bolometer by way of the induction-balance is practically rendered m'Z. Such a choking-coil is not limitedin its use to the system herein described, but may be effectively employed wherever a chokingcoil is reand its "local circuit.

quired'as,'for example, between a coherer- IOO 1. In a system of space telegraphy, an elevated conductor, aclosed resonant circuit, inductively associated therewith and attuned to the frequency of the-electromagnetic waves the energy of which is to be received, and an electror'eceptive device included in said resonant circuit and'adapted to utilize in its opera- 3. A'receiver forspace-telegraph signalscomprising a bolometerw ire or stripof-small cross section and low resistance, bridged across a narrow gap separating two metallic masses.

4. A receiver for space-telegraph signals comprising a bolometer wire or strip of small thermal time constant bridged across a narrow gap separating two metallic masses.

5. A receiver for space-telegraph signals comprising a bolometer wire or strip of small thermal time constant imposed upon two metallic masses separated by a narrow gap and forming an electrical connection between said metallic masses.

6. A receiver for space-telegraph signals comprising a bolometer surrounded by an atmosphere maintained at a low temperature by artificial means.

7. A receiver for space-telegraph signals comprising a bolometer surrounded by an atmosphere maintained at a constant low temperature by artificial means.

8. A receiver for space-telegraph signals comprising a bolometer surrounded by an atmosphere of inert gas.

9. A receiver for space-telegraph signals comprising a bolometer surrounded by an atmosphere of inert gas maintained at a low temperature by artificial means.

10. In a system of space telegraphy, an elevated receiving-conductor, a circuit, attuned by capacity and inductance to be more responsive to electromagnetic Waves of one frequency than to like waves of different frequencies, inductively associated with said conductor, and an electroreceptive device included in said circuit and adapted to utilize in its operation the dissipative energy of the electrical oscillations developed therein.

11. In a system of space telegraphy, an elevated receiving-conductor, a resonant circuit inductively associated with said conductor and attuned to the frequency of the waves the energy of which is to be received, means for swamping the effect of the mutual inductance between the elevated conductor and the resonant circuit and a bolometer fine wire or strip included in said resonant circuit.

12. In a system of space telegraphy, an elevated receiving-conductor, a resonant circuit inductively associated with said conductor by means of a step-down transformer and attuned to the frequency of the Waves the energy of which is to be received, and a bolometer fine wire or strip included in said resonant circuit.

13. In a system of space telegraphy, an elevated receiving-conductor, a circuit, attuned by capacity and inductance to be more responsive to electromagnetic Waves of one frequency than to like waves of different frequencies, inductively associated with said conductor by means of a step-down transformer, and an electroreceptive device included in said circuit and adapted to utilize in its operation the dissipative energy of the electrical oscillations developed therein.

14:. In a system of space telcgraphy, an elevated receiving-conductor, an clectroreceptive device adapted to utilize in its operation the dissipative energy of the electrical oscillations developed in the circuit in which it is included, and a plurality of resonant circuits. connected inductively in series by means of step-down transformers, interposed between said elevated conductor and said electrorcceptive device, said resonant circuits being attuned to the frequency of the waves the energy of which is to be received.

15. In a system of space telegraphy, an elevated receiving-00nductor serially connected with the primary winding of a step -down transformer; a resonant circuit including the secondary winding of said transformer and also including the primary winding of a second step-down transformer, and a second resonantcircuitincluding the secondarywindingof said second step-down transformer and also including an electroreceptive device adapted to utilize in its operation the dissipative energy of the electrical oscillations developed in said second resonant circuit, said resonant circuits being attuned to the frequency of the waves the energy of which is to be received.

16. In a system of space telegraphy, an elevated receiving-00nductor, an elcctroreceptive device adapted to utilize in its operation the dissipative energy of electrical oscillations developed in the circuit in which it is included, and means for conveying the electrical oscil' lations created by electromagnetic waves in said elevated conductor to said electroreceptive device at increased current.

17. In a system of space telegraphy, an elevated receiving-conductor, an electroreceptive device adapted to utilize in its operation the dissipative energy of the electrical oscillations developed in the circuit in which it is included, and a resonant circuit or a group of resonant circuits interposed between said elevated conductor and said QlQCtlOlCCOPtiVO device, said resonant circuits being attuned to the frequency of the waves the energy of which is to be received.

18. In a system of space telegraphy, an elevated receiving-00nductor, a resonant circuit inductively associated with said elevated conductor and attuned to the frequency of the waves the energy of which is to be received, and an electroreceptive device included in said resonant circuit and comprising a bolometer fine wire or strip surrounded by an atmosphere of inert gas maintained at a constant low temperature by artificial means.

In testimony whereof I have hereunto subscribed my name this eat day of l\ oven1bcr, 1903.

JOHN STONE STONE.

Witnesses:

G. A. HIGGINS, BRAINERD T. .lUDKINs. 

